Those old WinMX mp3s were sometimes inaccurately labelled, so it may not have been Horowitz, but it was a pretty good imitation if it wasn't.
I lost the original mp3 when my old PC crashed a couple of years ago. WinMX has since been shut down by a number of lawsuits.
I thought the Gottschalk was on the money from looking at the score, but I just had a listen to it on Naxos and it's a very different piece of music. Not bad though - Just wish he had made more of Yankee Doodle.
The 'Horowitz' recording does the Yankee Doodle bit as the middle section in that typical Stars And Stripes staccatissimo and surrounded by impossible sounding countermelodies (eg. 2m18s of S&S).
Sorry if the descriptions are on the vague side, but I can only go by recollection. I'm dying to hear this recording again. I just hope someone else has the same recording.
Cheers
Theodopolis